Assistance devices that effectively support an operating surgeon during a surgical procedure are known in the prior art. For instance, during a laparoscopic procedure, the surgeon views the surgical site indirectly via a display unit, for example a monitor, on which the laparoscopic instruments with which he is manipulating the anatomical structure in the patient are visible. The video image being displayed on the monitor in real time is recorded by a camera, which is part of an endoscope and is directed toward the surgical site.
During the procedure, the camera must be aimed at the surgical site in such a way that the target area being treated, along with the instrument tips and the anatomical structure to be manipulated, are located approximately at the center of the video image being displayed on the display unit. To change the image segment being viewed, the camera must therefore be moved in the body of the patient. The target area must then again be displayed at the center of the video image.
To allow the endoscopic camera to be repositioned in the desired manner, it is coupled to a manipulator, for example a robotic arm, which is adjusted in accordance with the desired camera movement. For this purpose, said manipulator is actuated by a manipulator controller via a control signal, which is obtained from the position of the instrument tip detected in the video image. An assistance device of the type described above is described, for example, in DE 199 61 971 B4.
Conventional assistance devices typically operate using markings that are attached to the instrument tip, thereby forming a distinguishing feature that allows the instrument tip to be detected in the video image. In place of such a marking, inherent characteristics of the medical instrument being used, such as its specific shape or specific color, may be used as a distinguishing feature. It is a drawback of these solutions, however, that the distinguishing feature to be identified is a characteristic peculiar to the instrument being used. Thus, it is not possible to identify any and all instruments.